1. Field of the Invention
The present invention relates to a drawing method for drawing an image on a two-dimensional screen such as on a television monitor device and a drawing device therefore, a computer readable recording medium having recorded therein a draw processing program to be executed on a computer, a program execution device for executing the draw processing program, and a draw processing program to be executed on a computer.
2. Description of the Related Art
There are accelerating trends toward higher integration and higher speed as for processors, memories and so forth of recent television game machine and personal computer. Such advancement enables real-time generation of a three-dimensional image having an excellent presence and perspective (feel of depth) and display thereof on a two-dimensional monitor screen.
For the case a three-dimensional image is drawn on a two-dimensional monitor screen, it is a general practice to subject a three-dimensional polygonal data to geometric processing such as coordinate transformation, clipping and lighting, and the obtained data are then transformed by perspective projection transformation.
For the case a three-dimensional image is drawn on a two-dimensional monitor screen, a widely adopted technique for expressing perspective or reducing affection by flicker caused by shrunk drawing of distant polygons is such that drawing the image in focus at a portion close to a virtual viewpoint but blurred at a portion distant from the virtual viewpoint.
In a conventional method for drawing a blurred image depending on the distance thereof from the virtual viewpoint, an original image are, for example, stepwisely shrunk corresponding to the distance from a virtual viewpoint and then enlarged again, and the enlarged images is synthesized with the original image according to distance in the depth direction (Z value) from the virtual viewpoint set for every pixel.
Such stepwise shrinking depending on the distance from the virtual viewpoint and corresponding enlargement, however, increases a load of image processing by the CPU, which will adversely affect other processing in progress of a game.
On the other hand, reducing the number of steps of shrinking and enlargement in the blurring in order to reduce the load of the CPU will be unsuccessful in obtaining a desired blurring effect and will thus fail in obtaining a desirable perspective.